U.S. patent number 7,298,056 [Application Number 11/162,177] was granted by the patent office on 2007-11-20 for turbine-integrated hydrofoil.
This patent grant is currently assigned to Integrated Power Technology Corporation. Invention is credited to Andrew Roman Gizara.
United States Patent |
7,298,056 |
Gizara |
November 20, 2007 |
Turbine-integrated hydrofoil
Abstract
A turbine integrated within a hydrofoil extracts energy from a
free-flowing motive fluid. In the preferred embodiment, the turbine
is of the crossflow variety with runner blades coaxial to the width
of the hydrofoil. The foremost edge of the hydrofoil comprises a
slot covered by a continuously adjustable gate for controlling the
overall drag imposed by the turbine. The hydrofoil mounts to a
sailing vessel by means of a gimbal on a structure affixed to the
hull, enabling the turbine to optimally respond to changes in
direction of the free-flowing motive fluid and facilitating
guidance and stability of the vessel. Both axes of the gimbal have
a combination of auxiliary generator and motor with a locking
mechanism. Engaging the motor and locking mechanism controls the
guidance and stability of the overall vessel, and the pitch of the
hydrofoil. Disengaging the locking mechanism and motor permits any
change in direction of the motive fluid to affect the gimbal
thereby extracting energy via the auxiliary generators. To further
control drag and output power over a range of flow velocities, the
preferred turbine comprises a DC generator with voltage feedback
controlling field excitation, coupled to a voltage and current
regulating circuit that performs electrolysis of water to produce
hydrogen fuel. The hydrogen fuel tank also functions as the
vessel's ballast having adjustable draft depending upon its
fullness. Integrated remote control simultaneously optimizes vessel
guidance, velocity, drag, stability, ballast depth, and
electrolysis processes.
Inventors: |
Gizara; Andrew Roman (Lake
Forest, CA) |
Assignee: |
Integrated Power Technology
Corporation (Lake Forest, CA)
|
Family
ID: |
37594903 |
Appl.
No.: |
11/162,177 |
Filed: |
August 31, 2005 |
Prior Publication Data
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|
|
|
Document
Identifier |
Publication Date |
|
US 20070046028 A1 |
Mar 1, 2007 |
|
Current U.S.
Class: |
290/54; 290/43;
114/244; 114/274 |
Current CPC
Class: |
B63J
3/04 (20130101); F03B 17/06 (20130101); C25B
1/04 (20130101); H02P 9/04 (20130101); B63H
9/04 (20130101); F03B 17/062 (20130101); F01D
25/24 (20130101); H02K 7/1823 (20130101); B63B
1/24 (20130101); Y02E 70/10 (20130101); F05B
2210/18 (20130101); B63B 2035/009 (20130101); Y02E
60/366 (20130101); B63B 2035/4466 (20130101); Y02T
90/40 (20130101); Y02E 10/30 (20130101); Y02E
10/28 (20130101); Y02E 10/38 (20130101); Y02T
90/38 (20130101); Y02T 70/583 (20130101); F05B
2220/61 (20130101); F05B 2240/931 (20130101); Y02E
10/20 (20130101); Y02E 60/36 (20130101); Y02T
70/5236 (20130101) |
Current International
Class: |
B63G
8/42 (20060101) |
Field of
Search: |
;290/43,44,54,55
;114/242,244 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2286570 |
|
Aug 1995 |
|
GB |
|
2365385 |
|
Feb 2002 |
|
GB |
|
2388164 |
|
Nov 2003 |
|
GB |
|
5-236698 |
|
Sep 1993 |
|
JP |
|
Other References
International Search Report for PCT/US2006/033373, mailed on Jan.
22, 2007, in 11 pages. cited by other.
|
Primary Examiner: Ponomarenko; Nicholas
Attorney, Agent or Firm: Knobbe, Martens, Olson & Bear,
LLP
Claims
What is claimed is:
1. A sailing vessel comprising a hull; a housing coupled to the
hull by a beam forming a hydrofoil configured to provide lift to
the hull, the housing comprising: at least first and second
openings configured to allow fluids to flow into the first opening
and out of the second opening; a turbine; and a generator coupled
to said turbine; wherein said turbine and generator are responsive
to the fluids to generate power.
2. The sailing vessel of claim 1 wherein said turbine is a
cross-flow turbine.
3. The sailing vessel of claim 1 further comprising leads
configured to charge a battery.
4. The sailing vessel of claim 1 wherein said housing further
comprises an electrolyzer for electrolyzing said fluid.
5. The sailing vessel of claim 4 wherein said housing further
comprises a storage area configured to store hydrogen produced by
the electrolyzer.
6. The sailing vessel of claim 4 wherein said electrolyzer
comprises anodes comprised of manganese dioxide.
7. The sailing vessel of claim 1 wherein said housing further
comprises a gate for adjusting the size of at least the first
opening.
8. The sailing vessel of claim 1 further comprising a feedback
system in communication with said generator, wherein said feedback
system is configured to control the average field winding current
to produce a constant voltage.
9. The sailing vessel of claim 1 further comprising a gimbal
coupling said housing to said beam.
10. The sailing vessel of claim 9 wherein said beam is adjustably
extendable.
11. The sailing vessel of claim 10 wherein said adjustably
extendable beam comprises means of energy extraction from
compression and tension forces acting upon said adjustably
extendable beam.
12. The sailing vessel of claim 1 further comprising a mast
comprising a lightning rod configured to store energy from
lightning.
13. A sailing vessel comprising a hull; at least two housings
coupled to the hull by beams forming a hydrofoil; at least one of
said housings comprising: at least first and second openings
configured to allow fluids to flow into the first opening and out
of the second opening; a turbine; and a generator coupled to said
turbine; wherein said turbine and generator are responsive to the
fluids to generate power.
14. The sailing vessel of claim 13, wherein at least one of said
housings is coupled to the starboard side of the hull and at least
one of said housings is coupled to the port side of the hull.
15. The sailing vessel of claim 13, wherein said housings provide
lift to the hull during operation.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is generally in the field of power plants.
More specifically, the present invention is in the field of
hydrokinetic generators with means to adapt to changes in
streamline direction and magnitude of a free-flowing motive fluid.
Most importantly, the present invention maximizes net energy by
utilizing a hydrokinetic generator mounted on a marine sailing
vessel that also limits drag on the vessel in a controlled
manner.
2. Description of Prior Art
Considering present humankind's primary source of energy, fossil
fuel can diminish to the point of negligible net energy within this
century; there exists a fundamental need for developing renewable
and sustainable sources of energy including further exploitation of
readily available known resources. More specifically, there exists
a need for a novel approach to ensure least impact to environment
and low civic infrastructure costs such that the energy investment
return is most quickly realized. Utmost, to optimally exploit
oceanic energy, which may be attained anywhere over approximately
three quarters of the surface of the planet thus availing vast
industrial growth potential, the main obstacle existing is the
delivery from such an expansive source of energy.
While many patents exist for harnessing energy from pneumatic and
hydraulic sources, relatively few have considered a mobile
structure to facilitate delivery of energy and maintenance and
servicing of the structure. For instance, wind turbines mounted on
abandoned off shore oil rigs, as well as both wind turbines and
hydrokinetic turbines mounted on structures essentially resembling
deep-sea buoys have begun to proliferate. These types of structures
obviously do not adequately address delivery of energy considering
their distance from the shore, the actual distribution center.
These structures also impede maritime traffic and present
maintenance difficulties especially in severe weather conditions.
Another limitation of this prior art overcome by the present
invention is that the density of water is approximately seven
hundred seventy five times greater than air and thus a wind turbine
must occupy an area seven hundred seventy five times greater than a
hydrokinetic turbine in order to yield equivalent power given equal
velocity of the motive fluids. The prior art structures utilizing
hydrokinetic turbines yield power limited by the velocity of the
motive fluid converted from wave motion alone. In contrast, a
sailing vessel of limited drag may achieve velocities greater than
the wind velocity thus illustrating one way in which the present
invention optimally uses the advantages of combining hydraulic and
pneumatic mediums. Even fewer patents so far have addressed the
need to reduce drag caused by the mobile structure while engaged in
the motive fluid.
The reduction of drag, the combined exploitation of hydraulic and
pneumatic energy mediums, and the integration into a singular
mobile combined generation and delivery system with means to
optimally respond in a controlled manner to changes in velocities
of the media exemplify the patentable novelty the present invention
holds over prior art.
SUMMARY OF THE INVENTION
The present invention achieves the goals of overcoming existing
limitations of prior art oceanic hydrokinetic and pneumatic power
generation systems foremost through integration into a singular
generation and delivery system to extract power from free-flowing
seawater while simultaneously exploiting wind energy. While prior
art exists which functions in free-flowing bodies of water or wind,
the novelty of this invention lies in its ability to respond and
adapt to any change in the magnitude and direction of the
streamlines of plural free-flowing motive fluids while controlling
drag caused by moving in any direction within the mediums of wind
and water. Through implementing a system to control vessel velocity
given input parameters such as wind velocity, seawater current
velocity, vessel mass and drag affecting actual velocity of the
vessel, and feedback of generator output voltages; this enables the
present invention to extract optimal energy from both pneumatic and
hydrokinetic sources. Controlling the drag also facilitates
maintaining overall stability and guidance of the vessel.
Secondly, because developing an integrated generation and delivery
system which optimally adapts to changes in both magnitude and
direction of the streamlines of plural free-flowing motive fluids
formed the basis of the guiding concepts of the present invention;
this readily avails the present invention the applicability to any
body of water anywhere. Thus, the present invention does not
require a large scale of infrastructure and therefore greatly
diminishes the environmental impact while attaining a positive net
energy earlier upon implementation.
Optimizing energy efficiency in the control of all processes
including drag, ballast depth, vessel stability and velocity, and
electrolysis of water in an integrated control loop positions the
present invention as desirable for implementation in gathering
energy for emerging power conveyance systems, especially hydrogen
fuel and fuel cell technology.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a general perspective view of a vessel
implementing an exemplary apparatus in accordance with a preferred
embodiment of the present invention.
FIG. 2 illustrates a perspective detailed view of a
turbine-integrated hydrofoil according to the preferred embodiment
of the present invention.
FIG. 3 illustrates a bottom view of the gimbal mounting means along
the mounting beam for the turbine-integrated hydrofoil in FIG. 2
according to a preferred embodiment of the present invention.
FIG. 4 illustrates a perspective cross-section view of two
positions of the gate for the turbine or electrolyzer according to
an embodiment of the present invention.
FIG. 5 illustrates a perspective view along the axis of the rotor,
a cross section of an impeller with runner blades within the
turbine according to a preferred embodiment of the present
invention.
FIG. 6 illustrates a top-downward view of the outline of the hull
and mounting of the vessel according to an alternate embodiment of
the present invention.
FIG. 7 represents a schematic view of a DC generator implementing
switch mode field excitation directly coupled to the output shaft
of the fluid coupler according to a preferred embodiment of the
present invention.
FIG. 8 illustrates the flowchart for control of the complete system
according to a preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed to a turbine-integrated hydrofoil
for adaptively extracting energy from plural free-flowing motive
fluids that continuously change direction and magnitude of flow.
The following description contains specific information pertaining
to various embodiments and implementations of the present
invention. One skilled in the art will recognize that the present
invention may be implemented in a manner different from that
specifically depicted in the present specification. Furthermore,
some of the specific details of the invention are not described in
order to maintain brevity and to not obscure the invention. The
specific details not described in the present specification are
within the knowledge of a person of ordinary skills in the art.
Obviously, some features of the present invention may be omitted or
only partially implemented and remain well within the scope and
spirit of the present invention.
The following drawings and their accompanying detailed description
are directed as merely exemplary embodiments of the invention. To
maintain brevity, some other embodiments of the invention that use
the principles of the present invention are specifically described
but are not specifically illustrated by the present drawings, and
are not meant to exhaustively depict all possible embodiments
within the scope and spirit of the present invention.
FIG. 1 illustrates a general perspective view of a vessel 100
implementing an exemplary apparatus in accordance with one
preferred embodiment of the present invention. FIG. 1 depicts three
turbine-integrated hydrofoils 101 engaged in the direction of the
vessel 100. The present invention may implement any number of a
plurality of turbine-integrated hydrofoils 101. The
turbine-integrated hydrofoils 101 couple to the vessel 100 through
corresponding beams 105 affixed to the hull 102 of the vessel 100.
FIG. 1 portrays a single hull 102 although implementation of a
multi-hull structure does not constitute a substantial departure
beyond the scope of the present invention. A design of adequate
buoyancy of the turbine-integrated hydrofoil 101 may supersede the
implementation of any hull whatsoever. Further description of means
of buoyancy within the turbine-integrated hydrofoil 101 and of an
alternate shape of the hull 102 follows in subsequent paragraphs,
FIG. 2, and FIG. 6. The length of beam 105 may extend to varying
distances from the vessel's center of gravity through variable
extension means 104 depending upon the velocity and stability of
the vessel 100. The variable extension means 104 may vary in length
through a controlled stabilizing locking motor mechanism not shown,
or through a hydraulic piston-driven turbine system not shown. The
hydraulic piston driven turbine system extracts supplemental energy
from the tension and compression forces on the variable extension
means 104 when drag varies from one hydrofoil 101 to the next
during a vessel 100 stabilizing process engaging plural
turbine-integrated hydrofoils 101. The beam 105 terminates at the
gimbal mounting means 103 further described in a subsequent
paragraph and in FIG. 3. Below the waterline, the output fuel tank
106 affixes to the hull 102 through variable extension means 107
which varies the draft of the output fuel tank 106 by varying
extension length depending upon vessel velocity and stability, and
mass of the output fuel tank 106 affected by fullness thereby
providing ballast. Sails 108 provide the ordinary means of
extracting energy from pneumatic sources. Because the hydrofoils
101 mount upon a beam extension means 104 of variable length, the
sails 108, while not necessarily drawn to scale in FIG. 1, may
significantly exceed the typical area of a sail for a vessel of a
given hull size as depicted in FIG. 1. Furthermore, implementation
of any area and material type for the sail 108 not explicitly
addressed herein does not constitute a departure beyond the scope
of the present invention. The mainmast 109 affixes the sail 108
employing means typically practiced in the art, though once again,
due to the additional stabilizing effect provided by the hydrofoil
mount beam variable extension means 104, the mainmast 109 may
significantly exceed the typical height of a mainmast 109 for a
vessel of a given hull size as depicted in FIG. 1. A lightening rod
110 mounts atop the mainmast 109 in order to extract additional
energy from electrical storm activity. Given a mainmast 109
extending to greater heights than typical mainmasts for a vessel of
the depicted hull size, and also in order to extract optimal
pneumatic and hydraulic energy the vessel 100 will plot a
trajectory towards maximal weather conditions likely including
electrical activity, the present invention thus extracts further
energy through lightening strikes to the lightening rod 110.
FIG. 2 illustrates a detailed perspective view of the
turbine-integrated hydrofoil 101, which provides a fundamental and
significant departure from prior art and considerable novelty in
the present invention. The dashed line 200-201 represents the axis
of rotation 216 of the entire assembly of the hydrofoil 101. To
minimize undesired mechanical oscillatory motion 216 that reduces
efficiency and induces stress, the dashed line traverses through
the center of gravity of the turbine-integrated hydrofoil. The
rotation means 215 likely comprises circular bearings and serves
two purposes. First, directly coupled through motor and locking
means not shown, the rotation means 215 can adjust the angle of
pitch of the hydrofoil 101 to optimize dynamic lift for variable
vessel 100 velocities. Secondly, once the locking means not shown
coupled to the rotation means 215 disengages, the motor not shown
coupled to the rotation means 215 may operate as a generator
extracting supplemental energy from rotational motion 216 caused by
changes in direction of the free-flowing motive fluid. One of
ordinary skill in the art will readily recognize the rotation means
215 forms one axis of a gimbal, a second axis formed by the gimbal
mounting means 103 depicted in FIG. 3 and described in a subsequent
paragraph. The present invention thus adapts to any change in
direction of the streamlines 202 of a free-flowing motive
fluid.
FIG. 2 further shows the streamline 202 of the free-flowing motive
fluid entering the gate 204 of the turbine-integrated hydrofoil
101, proceeding through the outline of the fluid coupler means 205,
and changing in pressure and velocity as indicated by the
streamline 203 in the draft section of the turbine of different
size and shape than the entering streamline 202. In the preferred
embodiment, the fluid coupler means 205 entails a cross-flow
impeller design as depicted in FIG. 5 and described in a subsequent
paragraph. As the flow passes through the fluid coupler means 205,
it impinges upon the lower surface 206 of the draft section of the
turbine whereupon the gate to the electrolyzer may be found. Both
the turbine gate 204 and the electrolyzer gate on lower surface 206
are illustrated in detail in FIG. 4. The electrolyzer preferably
sits in the area 209 between the lower surface 206 of the draft
section of the turbine and the outer lower surface 208 of the
hydrofoil 101 itself. One electrode 211 of plural electrodes and
the electrolyzer membrane 210 are shown and further comprise
temperature sensors not shown which in part determine the openness
of the electrolyzer gate. By flowing from the input gate in area
209 through the exit gate in area 212, the motive fluid of the
turbine also serves as electrolyte as well as forced convection
cooling fluid for the electrolyzer membrane 210 and electrodes 211.
The openness of the electrolyzer gate and the turbine gate 204
affects the overall drag of the hydrofoil 101, and thus besides
electrolyzer membrane 210 and electrode 211 temperature, the drag,
stability, and velocity of the vessel 100 represent input variables
into the control algorithm for opening the electrolyzer gate and
turbine gate 204. In the preferred embodiment, the anode electrode
211 is composed of, or plated with manganese dioxide to minimize
the amount of sodium hypochloride, NaOCl, also known as sodium
chloroxide or chlorine bleach that collects at the anode 211 while
operating in salt water. Hydrogen gas output from the electrolyzer
becomes sequestered in a storage tank 207 or in the area 213. The
hydrogen gas further enhances buoyancy of the overall hydrofoil
101. Obviously, any change in position of gates or area that the
electrolyzer occupies within the hydrofoil 101 in the preferred
embodiment does not constitute a substantial departure beyond the
scope of the invention.
The remaining features depicted in FIG. 2 include the external fins
214, and the support brace 217 directly coupled to the main strut
218. The main strut 218 directly couples to a rotating member 300
depicted in FIG. 3. FIG. 3 illustrates the rotational direction 301
allowed by the rotating member 300 affixed to the gimbal mounting
means 103. As previously described for the primary axis, the
rotating member 300 depicted in FIG. 3 affixed to the gimbal
mounting means 103 forms the second axis of a gimbal. The rotating
member 300 likely comprises circular bearings and serves two
purposes. First, directly coupled through motor and locking means
not shown, the rotating member 300 can adjust the angle of attack
of the hydrofoil 101 and thus with the external fins 214 behaving
as the keel board of the vessel 100, control guidance and stability
of the vessel 100. Secondly, once the locking means not shown
coupled to the rotating member 300 disengages, the motor not shown
coupled to the rotating member 300 may operate as a generator
extracting supplemental energy from rotational motion 301 caused by
changes in direction of the free-flowing motive fluid impinging on
the external fins 214. The present invention thus further adapts to
any change in direction of the streamlines 202 of a free-flowing
motive fluid. Let it further be known that given means to extract
supplemental energy from the tension and compression forces on the
variable extension means 104 and use of the external fins 214 and
rotating member 300, the utilization of the vessel 100 in a body of
free-flowing motive fluid of constant direction may entirely
obviate a sail 108 and mainmast 109.
FIG. 4 illustrates two positions of a suitable embodiment of a
mechanism for the gate to the electrolyzer or the turbine itself.
The left hand side of dashed line 400-401 portrays the view of the
gate in a closed position while the right hand side of dashed line
400-401 portrays the view of the gate in the open position. The
arrows 402, 403 indicate the streamline of either the free flowing
motive fluid 202 impinging on the turbine-integrated hydrofoil 101
itself, or the motive fluid 203 passing the gate of the
electrolyzer on the lower surface 206 in the draft section of the
turbine. Arrow 402 implies flow passing unabated over the closed
gate whereas arrow 403 implies partially diverting flow inward
while passing over an open gate. The blades 404 of the gate rotate
synchronously upon an axis 405 depending upon the required
adjustment. Arrow 406 indicates a closed gate adjusting to a more
open position while arrow 407 indicates an open gate adjusting to a
more closed position. FIG. 8 and subsequent paragraphs furnish
further detail into the algorithm that determines the openness of
each respective gate. While the gate mechanism presented in this
specification likely provides adequate if not optimal
functionality, the use of any other gating means not explicitly
described herein does not constitute a substantial departure beyond
the scope of the present invention.
FIG. 5 illustrates a perspective view of a fluid coupler, a
cross-flow impeller looking along the axis of the rotor within the
turbine. Dashed line 200-201 indicates the axis of rotation as
stated before and viewed in FIG. 2 where the outline area of the
fluid coupler 205 first became manifest. Here FIG. 5 shows a
cross-sectional view of the rotor 500 as motive fluid 202 passes
over the plurality of runner blades 501 to finally exit as draft
flow 203 after depositing most energy in the form of both impulse
force impinging upon the blade 501 and reactive force when leaving
the blade 501. As this curved form of cross-flow impeller is well
known within the public domain as derived from the Pelton water
wheel concept for optimal energy extraction, the specification
herein thus requires no further description. In light of the
aforementioned, the modification of Pelton runner blades in the
preferred embodiment is purely exemplary, illustrative and not
restrictive. As previously stated, the fundamental goal of the
present invention is to attain the highest possible net energy, in
other words, highest return on investment in terms of energy,
through implementing the simplest design. While the impeller herein
presented likely provides optimal functionality, let it hereafter
be known that any impeller, whether or not responsive to impulse
and reaction forces, within a turbine-integrated hydrofoil
responding to changes in direction and magnitude of the streamlines
of a free-flowing motive fluid does not constitute a substantial
departure beyond the scope of the present invention.
This specification now refers to FIG. 6, a top-downward view of the
outline of an alternate embodiment of the hull and mounting system.
As previously stated, the vessel 100 may possess a single hull or a
multiple hull structure, or no hull whatsoever given adequate
buoyancy of the turbine-integrated hydrofoil 101. The outline of
the hull 102, indicated by lines 600 in FIG. 6 represents a most
agile structure for maneuverability, guidance and adaptation to
changes in direction of pneumatic and hydraulic motive fluids given
the gimbal mounting means 103 previously described for the
turbine-integrated hydrofoil 101. The line 601 represents the keel
board of the hull, mainly shown to clarify the view of the
structure of the hull 102 in FIG. 6, which otherwise serves no
practical purpose given the external fins 214 of the
turbine-integrated hydrofoil 101 depicted in FIG. 2. Lines 602 and
603 represent alternate embodiments of the beams 105 and variable
extension means 104 previously described. Line 603 thus represents
a pinion member acting upon a rack gear in the middle of line 602
to increase or decrease the length of lines 602. Increasing the
length of any singular line 602 increases the area of the triangle
602 formed by plural lines 602, thus moving the gimbal mounting
means 103 of the turbine-integrated hydrofoil 101 located at the
vertices of the triangle 602 away from the center of gravity of the
vessel 100. The pinion member represented by line 603 possesses the
same features and characteristics of the variable extension means
104 of FIG. 1 such as a locking motor mechanism or a generator when
unlocked to extract supplemental energy when tension and
compression forces act upon the variable extension means. One may
note that multiple sides of the triangle formed by lines 602 must
act synchronously, with one advantage being less stress to any one
member due to distribution of forces among multiple members. Let it
be know that the hull and mounting system presented in FIG. 1 and
FIG. 6 in the preferred embodiment is purely exemplary,
illustrative and not restrictive and any alternate hull and
mounting system does not represent a significant departure beyond
the scope of the present invention.
FIG. 7 depicts a coupling configuration and energy extraction means
from the impeller through to the output conditioning circuitry of
the electric generator. FIG. 7 shows the generator rotor shaft 500
directly coupling to a DC generator 700. The DC generator 700 may
also function as a motor by means of reversing armature current and
with the use of the external fins 214 and rotating member 300, may
enable guidance and stability of the vessel 100. The impeller, not
shown in FIG. 7 in order to maintain simplicity, physically
occupies the outline area 205 within the turbine-integrated
hydrofoil 101, while the shaft 500 extends along the axis of
rotation, line 200-201 as depicted in FIG. 2 and FIG. 5. The DC
generator 700 may be any of available forms of DC generator,
including but not limited to a commutated or
semiconductor-rectified generator, and as shown with a
separately-excited or else preferably with a self-excited shunt
field winding 721 configuration chosen for its combined simplicity
and relatively constant voltage independent of load current. The DC
generator 700 thus produces a speed-dependent DC voltage across its
armature leads, positive 701 and negative 702, that feeds the power
filtering elements, the inductor 703 and the capacitor 705. Though
two armature leads 701, 702 imply a single-phase machine, this is
purely exemplary, and no predetermination is placed on the number
of phases of the machine in the preferred embodiment. The filtering
performed by the inductor 703 and the capacitor 705 minimizes spurs
in the electrical waveform caused by commutation. The preferred
embodiment of this invention samples the filtered DC waveform at
node 704 filtered by inductor 703 and capacitor 705 referencing the
negative armature lead 702 to local ground 707 to form feedback
that controls the average current through the field winding 721.
The feedback that controls the average field winding 721 current
thus controls the torque opposing the impeller rotation thus
controlling drag of the vessel 100 and ultimately the armature
voltage depending on impeller rotational velocity and load
current.
As previously mentioned, this form of feedback regulation allows
relative scaling of mechanical parameters such as openness of the
turbine gate 204 affecting vessel 100 drag in a coarse manner,
ultimately affecting the power extractable for given pneumatic and
hydraulic motive fluid energy levels. For power output means that
draw a constant load current, this feedback control of field
winding current can compensate for fine, instantaneous variation in
the velocity and pressure of the free-flowing motive fluid 202 to
produce a relatively constant armature voltage. This feedback
control can also most quickly respond accordingly to changes in the
free-flowing motive fluid 202 that impart varying levels of torque
on the impeller affecting vessel 100 drag in a fine manner and thus
avert potentially fatigue-inducing torque on the impeller during
extreme conditions characterized by bow breaching and plunging
motion imparting varying force on the turbine-integrated hydrofoil
101. For instance, when the average voltage of the sampled,
filtered DC waveform at node 704 exceeds a given threshold, the
feedback control will reduce the average current passing through
the field coil 721 which in turn, reduces the torque on the
impeller while reducing the average armature voltage. Likewise,
when the average voltage of the sampled, filtered DC waveform at
node 704 recedes below a given threshold, the feedback control
increases the average current passing through the field coil 721,
which in turn, increases the torque on the impeller for the benefit
of increasing the average armature voltage. While load or armature
current, i.e. the electrical current leaving the filtered node 704
and entering the output power conditioning means 724 may vary,
responding to load current change may take a subordinate priority
compared to responding to changes in motive fluid 202 pressure in
order to avert fatigue on the impeller. In one case, an increase in
extractable energy from the free-flowing motive fluid 202 or
relative velocity of the vessel 100 coincides with an increase in
demand for load current, therefore necessitating little change in
average current passing through the field coil 721. Similarly, a
decrease in extractable energy or relative velocity of the vessel
100 from the free-flowing motive fluid 202 coincides satisfactorily
with a decrease in demand for load current again necessitating
little change in average current drawn through the field coil 721.
However, given the extractable energy from the free-flowing motive
fluid 202 increases or decreases contrary to a decrease or increase
in demand for load current, these situations can elicit limitations
in the control loop response. These limitations may manifest in
terms of delayed response time, that is, control loop parameters
such as loop bandwidth and damping factor that primarily concern
stability may slow a response time, producing inadequate transient
output voltage or else excessive transient output voltage given a
lesser bandwidth or incorrect damping factor. In addition, the
design must take into careful consideration the overall headroom
for meeting system demands during such instances, and thus varying
loads require more design complexity. Therefore the preferred
embodiment of this invention powers output means drawing constant
current for optimal power conditioning for application to loads
such as an electrolyzer, with the relative velocity of the vessel
100 also an input parameter in the overall control loop for the
complete system as described in subsequent paragraphs and FIG.
8.
Proceeding further along the path of the local feedback loop, FIG.
7 depicts two points on the filtered node 704 where sampling
occurs. The path including the resistors 710, 712 and the capacitor
711 constitute the voltage sampling node of a typical feedback loop
with frequency compensation. The network of these resistors 710,
712 and the capacitor 711 along with the error amplifier 709 and
its own feedback loop represented by the capacitors 714, 715 and
the resistor 716 form the feedback section of a prior art switch
mode power supply. Given the fixed internal reference voltage 713
into the non-inverting input of the error amplifier 709, resistor
710 along with resistor 708 compose a voltage divider that sets the
optimal voltage on the filtered node 704 that feeds the output
power conditioning means 724 while this control loop responds to
variations in the velocity of the motive fluid 202. The reference
voltage 713 multiplied by the quantity of one plus the ratio of
resistor 710 over resistor 708 determines the optimal value of the
output voltage of the filtered node 704 that the control loop
maintains despite changes in input energy. The other sampling node
includes the Zener diode 706 that quickens the response to
over-voltage conditions at the sampling node 704. Resistor 708 must
be of correct value in order to allow the Zener current to flow
through the diode 708 given this over-voltage condition. The design
of the frequency compensation of this error amplifier must also
take into account the junction capacitance, though often negligibly
small, seen across the Zener diode 706 and parallel to resistor
710. Resistors 712 and 716 and capacitors 711, 714, 715 form the
frequency compensation of the error amplifier 709 within the
feedback loop of a prior art switch mode power supply. While tuning
these frequency compensation components is not germane to the
specification of the present invention and is elsewhere covered in
detail, this specification will now disclose some general
observations regarding it. Uncompensated, the filter components,
the inductor 703 and the capacitor 705 produce a complex pole pair
at their resonant frequency given by one over the quantity of two
times pi times the square root of inductance times the capacitance.
The filter capacitor 705 also places a zero above the pair of poles
at a frequency given by one over the quantity of two times pi times
the capacitance and the value of the capacitor's 705 equivalent
series resistance, "ESR". Generally as a goal in compensation, two
zeroes are added near the filter resonant frequency to correct the
sharp change in phase near that frequency and an open-loop unity
gain frequency is chosen to exist at a frequency about ten times
greater than the resonant frequency but less than about 10% of the
switching frequency. The overall gain of the error amplifier 709,
the filter components comprising the inductor 703 and capacitor
705, the two zeroes added plus the gain of the integrator created
by the compensation network that sets open-loop unity gain
frequency preferably sums to zero at the unity gain frequency. The
integrator gain is given by 1/(2(pi)(Fo)(R710(C714+C715))) where Fo
is the open-loop unity gain frequency. The frequency of the output
filter compensating zeroes equals 1/(2(pi)(R716)(C715)) and
1/(2(pi)(R710+R712)(C711)) and these zeroes are understood to add
to 40 dB per decade of gain. A pole also exists in the compensation
network and its frequency is chosen to coincide with the zero
formed by the output capacitor 705 and its equivalent series
resistance "ESR". This compensating pole frequency equals
1/(2(pi)(R712)(C711)). A final pole in the compensation network
exists at the frequency 1/(2(pi)(R716)(C714||C715)) and is selected
to be about 3/4 Fs, three-quarters of the switching frequency to
reduce switching noise into the error amplifier 709. While it is
understood the precise placement of the pole frequencies,
integrator frequency and zeroes frequencies is not of utmost
criticality, care must still be taken to follow the aforementioned
feedback loop frequency compensation practices to yield best power
supply response and stability, and particularly a relatively
constant output voltage 704 over the widely varying angular
velocity of the rotor 500 resulting from the wide variation of
energy within the free-flowing motive fluid. In the past, stability
problems have risen due to a negative resistance oscillator formed
by cascading switch mode power supplies. For example, the second
switch mode power supply in FIG. 7, the output power conditioning
means 724, presents a negative resistance because its input current
actually decreases with increased input voltage, which in turn may
cause instability by adding right-hand s-plane poles in the
characteristic equation of the control loop. To prevent this form
of instability, the design must ensure the magnitude of the complex
impedance of the source, i.e. the DC generator 700 along with the
power filtering elements, the inductor 703 and the capacitor 705,
is much less than the magnitude of the input impedance of the
output power conditioning means 724 over the entire frequency band
of interest, from DC to the unity gain frequency of the feedback
loop of the output conditioning means 724. Careful consideration to
all the aforementioned stability criteria ensures long-term
reliability and optimal energy extraction over the widest possible
range of velocity of the motive fluid 202.
Proceeding further along the feedback path depicted in FIG. 7,
after the error amplifier 709, a pulse width modulation or pulse
frequency modulation controller 717 exists primarily to convert the
analog error signal output of the error amplifier 709 into pulses
which, after getting conditioned to source and sink large impulses
of current by the gate driver buffer 718, drive the gate of the
field coil current switching field effect transistor 719,
ultimately determining the average current drawn through the field
winding 721 of the DC generator 700. The design of the pulse width
modulation or pulse frequency modulation controller 717 preferably
implements an analog comparator, not shown, that sets and resets
logic according to the value of the sampled voltage 704 compared to
a fixed reference. In this case, the analog comparator, not shown
within block 717, receives at its inverting input, the voltage
signal output from the error amplifier 709. The non-inverting input
of the analog comparator, not shown, receives a DC voltage signal
equal to that of the voltage reference 713, in the same manner as
the error amplifier 709. The analog comparator within the pulse
width modulation or pulse frequency modulation controller 717 thus
compares the inverted output of the error amplifier 709 to a
voltage equal to DC reference 713. Since the comparator within the
pulse width modulation or pulse frequency modulation controller 717
is an inverting amplifier referenced to the voltage reference 713,
the filtered output voltage 704 once divided by resistors 710, 708
gets inverted through the error amplifier 709, and this output gets
inverted by this comparator. Therefore, the comparator output
within the pulse width modulation or pulse frequency modulation
controller 717 is a logic high signal when the filtered output
voltage 704 is above the set voltage and a logic low signal when
the filtered output voltage 704 is below the set voltage. This
comparator output logic signal is routed out through logic means
that finally inverts the signal into the gate driver 718. Thus when
the filtered output voltage 704 exceeds the set voltage, the logic
means resets and along with the output of the modulation controller
717 and inputs to the gate driver 718, goes low, disabling current
flow through the field coil current switching transistor 719. The
logic means within the pulse width modulation or pulse frequency
modulation controller 717 preferably permits the controller 717 to
operate in an energy saving "pulse skip" mode. When the output
voltage 704 exceeds the set voltage, skipping pulses saves the
energy needed to charge and discharge the gate of the field coil
current switching transistor 719. As previously stated, the
relative velocity of the vessel 100 presents an input parameter in
the overall control of the vessel 100. Here in the pulse width
modulation or pulse frequency modulation controller 717, the input
parameter of vessel 100 relative velocity may induce pulse skip
operation. When the relative velocity of the vessel 100 recedes
below a given threshold, the pulse width modulation or pulse
frequency modulation controller 717 may thereby minimize energy
lost in field coil 721 current as well as reduce drag on the vessel
100. Let it hereafter be known that this means of controlling the
average field coil current using switch mode techniques is strictly
exemplary and not restrictive, and therefore any changes in
configuration, such as but not limited to, choice of pulse width
versus pulse frequency modulation, or the polarity of the output
logic and according choice of N-type or P-type channel material of
the field coil current switching transistor 719, does not
constitute a substantial departure beyond the scope and spirit of
the present invention.
While FIG. 7 depicts a separately excited field coil as the means
of field coil excitation, a self-excited shunt field winding likely
proves equally effective, if not more readily realizable due to the
amount of current passing through the coil and convenience of not
needing the physical space a separate supply 722 occupies. Note
that while FIG. 7 also depicts the catch rectifier 720 as a
Schottky diode, that a synchronized switching transistor may be
implemented in its place at the expense of greater complexity in
the logic of the controller 717 and an additional gate driving
buffer similar to gate driver buffer 718 but for the benefit of
increased power efficiency. As well known by those skilled in the
art, because the field coil 721 is inductive, when the current is
switched, the field coil voltage is reversed proportional to the
inductance multiplied by the change in current with respect to
time. Using a simple catch rectifier 720 can protect the switching
transistor 719 from over voltage while feeding that stored energy
back to recharge the separately excited field winding source 722 or
back into the armature terminal 701 in the case of a self-excited
shunt field winding, thereby returning the stored energy in the
field coil 721 back to the system, increasing the system power
efficiency. A synchronous switching rectifier that has a lower
voltage drop across it depending upon drain to source on-resistance
and rectifying current compared to the catch rectifier 720 gains
further efficiency. The complexity of the synchronous rectifier
lies in the precision required to prevent the field coil current
switching transistor 719 including its gate capacitance from having
an on-time that coincides with the on-time of the transistor
including its gate capacitance that replaces the catch diode 720.
Having on-times that coincide effectively short-circuits the field
winding leads and thus short-circuits the field winding excitation
source. Conversely, the longer delay in turning-on the synchronous
rectifying transistor reduces the gain in efficiency. Digital
timing circuitry within the controller 717 may achieve the goal of
precise timing necessary, given a known tolerance for the gate
capacitances of the switching transistors. Whether the system of
controlling average field coil current implements a simple catch
diode or a synchronous rectification circuit, both circuits remain
within the scope of the present invention.
While this specification previously presented a chopped field coil
current controlled DC generator as the preferred embodiment,
equivalent generator configurations exist within the scope of the
present invention. In one embodiment, the generator 700
alternatively exists as an AC induction generator of adequate
number of poles such that its synchronous speed, which determines
whether the AC machine is operating in its generator or motor
region according to its torque-slip curve and is inversely
proportional to the number of poles, is well below the average
rotational velocity of the rotor 500 and therefore the AC machine
operates with positive slip as a generator. What makes the AC
induction generator desirable is its economical, reliable
construction and widespread use, rendering this type of generator
easily attainable and cost effective. In the case of unavailability
of an AC induction generator of sufficient number of poles for an
adequately low synchronous speed to operate with positive slip
given the average rotational velocity of the rotor 500, the AC
induction generator indirectly couples to the impeller through a
gear system. This gear system increases the rotational velocity of
the rotor shaft 500 with respect to the impeller. The gear system
likely occupies the outline area of the fluid coupler 205 in
proximity to the generator 700. In order to directly apply the
voltage from the AC induction generator to the load through wires
725, 726, the electrical circuit represented by output conditioning
means 724 contains a speed dependent switch that receives an input
signal from a velocity transducer sensing the rotation of the rotor
500 in the outline area of the fluid coupler 205. The velocity
transducer output signal therefore also needs to physically
traverse the same path as the leads 701, 702 either on its own
conductor or modulated upon the armature coil power current. This
speed dependent switch affords highest efficiency and protection
such as when the coupler shaft has inadequate velocity for positive
slip, or there exists a fault condition on either side of the
output conditioning means 724, the AC generator becomes
disconnected from the load. This gear system including automatic
transmission to change the impeller to rotor gear ratio to achieve
constant output voltage amplitude over varying fluid velocities,
rotational velocity transducer, and speed dependent switch
effectively replaces the filtering components 703, 705, and the
entire field current controlling feedback loop of the previously
described DC generator system. The output conditioning means 724
could thus be physically located in the hull 102 away from the
generator unit, with the leads 701, 702, routed from the generator
700, through the support structure 217, 218, 103, out along the
beam 105 through the extension means 104 to the hull 102 location
of the output conditioning means 724. As with the leads before, the
output conditioning means 724, though only a pair of wires 725, 726
is shown implying a single-phase system, this is purely exemplary
with no predetermination of the number of phases that may be
applied to the utility power grid.
Returning to the DC generator implementation, a variety of loads
may be applied by connection to the leads 702, 704 depending upon
end user needs. Examples of loads include charging any variety of
available chemistries of battery, or the leads 725 and 726
themselves terminating as the electrodes in the process of
electrolysis of water to produce hydrogen fuel. In both cases here,
the output means 724 will likely require the protection of the
transient voltage suppressor 723, shown in FIG. 7 as a Zener diode,
from inductive spikes caused by commutation. Here in these examples
of output loads as in all foregoing descriptions, the local ground
707 attached to lead 702 purely references the negative
differential voltage output of the generator 700 and all other
associated references in the field coil current controlling
feedback system, not ordinarily referenced to true earth ground and
thus not the chassis ground potential of the turbine-integrated
hydrofoil 101 and for that matter, quite likely completely isolated
from the negative differential voltage lead 726 from the output
power conditioning means 724 which may or may not be referenced to
a true earth ground potential.
In the case of the load being the charging batteries, the output
conditioning means 724 could occupy a physical location within the
turbine-integrated hydrofoil 101 in the instance of the battery
being the excitation source 722 for another DC generator 700. But
in other applications, because the process of battery charging
generally requires low-error voltage sensing at the battery
terminals and low-error temperature sensing from a thermistor
within the cell packaging powered by an accurate reference, the
design more feasibly and economically locates the charger section
of the output power conditioning means 724 in proximity of the
battery unit charging in the hull 102. Therefore the leads 725, 726
likely route high voltage from the output power conditioning means
724, through the support structure 217, 218,103, out along the beam
105 through the extension means 104 to the hull 102 location of the
battery and associated charger.
In the preferred embodiment, the load is the current required to
perform electrolysis on water to produce hydrogen fuel. This
process achieves a high efficiency due to inherent advantages in
the preferred embodiment of the present invention. Seawater is
naturally electrolytic thereby reducing chemical processing costs;
and advanced electrolysis methods allow for a voltage as little as
one and a half to two volts applied across the electrodes, which
the generator 700 in the self-excited shunt field winding
configuration can easily provide over a wide range of rotational
velocities of the rotor 500. Given the requirements for such a
system for electrolysis, the output conditioning means 724 in one
case consists of simply a very high efficiency synchronous switch
mode buck or in other words, step-down DC-to-DC converter, with
some form of current regulation, to provide the appropriate voltage
to the electrodes 725, 726 to perform electrolysis. In this case,
synchronous switch-mode DC-DC conversion cannot provide isolation
of the local ground 707 from true earth ground, which may or may
not be tolerable for the configuration of DC generator 700
implemented, though desirable due to its simplicity and optimal
efficiency. If the DC generator 700 absolutely requires ground
isolation, then a flyback or forward DC-DC converter with
synchronous rectification within the output power conditioning
means 724 achieves the next highest efficiency. Because this output
power conditioning means 724 is relatively simple and compact, it
can occupy an area adjacent to the generator 700 within the
turbine-integrated hydrofoil 101, with the leads 725, 726 routing
conditioned DC power to the electrodes contained within the
appropriate sections of the electrolyzer. For simplicity, the
system preferably reduces wire losses by minimum distance routing a
low voltage and high current through copper bars 725, 726 to the
electrolyzer where the power is then directly applied to the
electrodes 211. The leads 725, 726 terminate as the electrodes,
particularly the anode and cathode, respectively, for the
electrolyzer, and thus the anode 725 references to true earth
ground as the hydrogen collects at the cathode 726 while the system
isolates both the gas and electrical potential at the cathode 726
from the surrounding environment. One means of using seawater for
hydrogen electrolysis consists of admitting seawater through a
filter membrane in a reverse osmosis process for desalination then
adding potassium hydroxide as an electrolyte for increased
electrolyzer efficiency. In the preferred means, the filter
membrane is coarse enough to allow seawater with salt less the
silica particulate, and the anode 725 is plated with manganese
dioxide to minimize the amount of sodium hypochloride, NaOCl, also
known as sodium chloroxide or bleach that collects at the anode
725. This preferred electrolysis method saves the cost in energy to
perform reverse osmosis desalination and processing the sodium
chloroxide by-product otherwise an environmental contaminant.
Alternately, the output power conditioning means 724 may take the
AC voltage produced by an AC induction generator in place of the DC
generator 700 from leads 701, 702 and full-wave rectify the AC
voltage into a DC voltage, then filter and further regulate the
voltage and current for optimal power conditioning for application
to loads as described in the foregoing paragraphs regarding DC
power generation.
FIG. 8 illustrates the overall control of all the components
described thus far of the complete turbine-integrated hydrofoil for
adaptively extracting energy from a free-flowing motive fluid that
continuously changes direction and magnitude of flow. While FIG. 8
displays a flowchart, which is ordinarily associated with a
computer program running in software, the algorithm delineated may
be implemented with any combination of hardware or software such as
linear or analog circuits or discrete digital circuits or an
integrated central processing unit, or a microprocessor. A central
processing unit or microprocessor affords the advantage of
convenient means to gauge, test, and remotely communicate using
well-defined existing wireless standards to a central service
logging and energy distribution location, the state of any part or
process of the system, including but not limited to functionality,
guidance, stability, drag, velocity, or fullness of batteries or
hydrogen fuel tanks. Furthermore, a local central processing unit
or microprocessor may receive control signals guiding the vessel
100 towards maximal weather conditions from a remote control and
service facility with means to track weather conditions. Such
remote control means could permit unmanned operation of the vessel
100. From the start 800, the controller is continuously sampling
and storing 801 such variables as position, velocity, acceleration,
weight, and level of vessel; velocity of motive fluids; armature
voltages; fuel tank fullness; electrolyzer temperature; and energy
efficiency. From the sampling and storing 801 processes, the system
control algorithm proceeds in two concurrent paths through the
remainder of the flowchart. While not specifically stated in block
801, it may be assumed all sampled variables including the signals
representing various input parameters including the armature
voltage are sampled and stored in a likewise continuous, concurrent
manner as implied by the looping arrow exiting only to return to
the upper right corner of block 801. In the preferred embodiment,
the period for sampling the motive fluids velocities has a time
resolution necessary to react to and control mechanical processes,
ordinarily sampling at an approximate frequency of about a hundred
times a second, or a period of about ten milliseconds, with a small
deviation allowable possibly due to the convenience of a local
non-integer multiple frequency digital clock from which to derive
this sampling clock frequency. This algorithm then averages the
samples over a space of five to ten samples, this average
representing a single sample in order to reduce the effects of
noise. It is reasonable that the processes controlling motive fluid
related adjustments such as turbine gate openness in block 802 need
to occur, or most efficiently occur for that matter, no more often
than ten to twenty times a second. The vector sum of plural motive
fluid velocities is then computed to determine the vessel 100
trajectory to plot for optimal energy extraction by directing
towards the highest relative vessel 100 velocity vector. This
highest relative vessel 100 velocity vector then gets communicated
back to a central remote control facility if implemented.
In practically all conceivable embodiments, there always exists the
path that serves to adjust the field coil 721 current to optimize
generator 700 armature voltage, while minimizing the necessary
torque exerted on the impeller and drag on the vessel 100 over a
range of relative velocities of the free-flowing motive fluid 202.
Thus in the flowchart of FIG. 8, the path proceeds from the
sampling block 801 to the process block 802, where the
instantaneous magnitude of the sampled generator armature voltage
is compared to an upper threshold. This upper threshold likely
equals in excess of one hundred percent of, but less than two
times, the rated voltage of the generator 700. Various types of
circuits may perform this comparison through either digital
sampling followed by numeric comparison or through analog means to
control the average field coil 721 current such as the control
feedback loop previously described with FIG. 7. Hence, the outcome
of this comparison in block 802 determines whether to increase or
decrease the average field current accordingly. Using means
described previously and depicted algorithmically in FIG. 8, this
block 802 exists to process the sampled instantaneous magnitude of
the output voltage to determine the average field coil 721
excitation current by means of feedback control processes applied
in order to optimally extract energy from a free-flowing motive
fluid. If implemented digitally, the number of samples per second
corresponding appropriately to slightly greater than two times the
unity gain loop bandwidth previously described, defines the
sampling period per the Nyquist criterion. This digital algorithm,
like the preceding analog circuitry, allows the generator to
produce a maximum voltage while mitigating the risk of fatigue upon
the impeller 205 throughout the extremes of usable flow, while also
minimizing drag on the vessel 100 throughout the range of vessel
100 relative velocities.
The previously described paths through the flowchart of FIG. 8
perform mathematical manipulations on sampled output voltages of
sensors in order to determine the appropriate course of action. It
shall be known that any of the paths could share the outputs of
these mathematical functions in order to improve the overall
control algorithm. The previously cited example of this refers to
when the relative velocity of the vessel 100 recedes below a given
threshold, the pulse width modulation or pulse frequency modulation
controller 717 may skip pulses that determine the generator average
field coil 721 excitation current to minimize energy lost in field
coil 721 current as well as reduce drag on the vessel 100. FIG. 8
further shows by decision block 803 how the magnitude of vessel 100
relative velocity may feed into the control of most other
processes. Block 804 deals with insufficient magnitude in vessel
100 velocity, whereby reduction in vessel 100 drag is in order to
increase velocity, or minimize vessel 100 extreme instantaneous
instability, hence reduce the average field coil 721 to reduce
torque on the impeller 205 as well as close the turbine gate 204
and the gate to the electrolyzer depending upon temperature. Block
804 suggest two other means of reducing vessel 100 drag depending
upon vessel 100 stability thereby increasing velocity including
reducing the distance of the hydrofoil from the center of gravity
of the vessel 100, along with lifting the ballast 106. Block 804
also suggests adjusting the pitch of the hydrofoil 101 to improve
dynamic lift at the lower vessel 100 velocity. Block 805 deals with
optimizing extractable energy once the vessel 100 attains
sufficient velocity for the hydrofoils 101 to provide maximum
dynamic lift. This action includes opening the turbine gates 204
and increasing the average field coil 721 excitation current
resulting in increased armature voltage from the generators 700.
Another input parameter into this block 805 comprises vessel 100
stability, consisting of a computed standard deviation of level
over many samples as sensed by accelerometers, gyroscopes,
camera-based pattern recognition means, or any other presently
available inertial displacement sensing means. In block 805, vessel
100 stability and velocity form input parameters into control of
distance of hydrofoils 101 from the center of gravity of the vessel
100 and control of ballast draft itself having a third input
variable of fuel tank 106 fullness. Decision block 806 makes a high
level decision affecting vessel 100 trajectory based on tank 106
fullness. If the tank fullness is below a given threshold as shown
in block 807, the vessel 100 stays its present course towards
maximal weather conditions or maximal relative velocity vector as
computed in block 801. If the tank fullness appears above a given
threshold, the vessel 100 should plot a trajectory back towards the
central distribution destination to dock its payload, all the while
adjusting ballast 106 draft according to aforementioned stability
computations. While not explicitly depicted for sake of clarity in
the flow diagram of FIG. 8, it may be inferred that any deviation
of the algorithm to include the additional use of these function
output variables in decision blocks, or for that matter, use of a
singular central processor to also concurrently perform these and
other control tasks not explicitly depicted, such as, but not
limited to: charging batteries; or performing electrolysis;
maximizing energy efficiency; or electronic means of vessel 100
velocity, drag, stability, or guidance control; or logging
communications; does not constitute a substantial departure beyond
the scope of the present invention.
From the detailed description above it is manifest that various
implementations can use the concepts of the present invention
without departing from its scope. Moreover, while the invention has
been described with specific reference to certain embodiments, a
person of ordinary skill in the art would recognize that
significant alterations could be made in form and detail without
departing from the spirit and the scope of the invention. The
described embodiments are to be considered in all respects as
illustrative and not restrictive. It shall also be understood that
the invention is not limited to the particular embodiments
described herein, but is capable of many rearrangements,
modifications, omissions, and substitutions without departing from
the scope of the invention.
Thus, a turbine-integrated hydrofoil for adaptively extracting
energy from a free-flowing motive fluid that continuously changes
direction and magnitude of flow has been described.
* * * * *